[CT Birds] Thoughts on Bird Numbers
PCOMINS at audubon.org
Tue Mar 20 12:14:29 EDT 2007
Thanks for those thoughts and excellent tips on keeping good records. I don't want to minimize the contributions that 'citizen scientists' can make towards inventory and monitoring efforts though. I also certainly don't want to minimize the importance of keeping good records like you do, but I don't want people to think that keeping records of casual observations has no value at all.
I also think we need to make a distinction between 'inventory' and 'monitoring'. If your goal is to be able to track trends with some degree of certainty, you do need to carefully design your survey methods. This is why the Breeding Bird Survey, while it does have some serious limitations, is a such valuable tool to determine trends with at least some degree of certainty.
I think that even the most casual observations can be quite valuable though when it comes to making a first cut at an inventory of key places of conservation importance. Having the data from casual observers can give us a good idea of where to target more structured inventory efforts in order to identify the sites that may be most important to migrant, wintering or nesting birds. For example, simply having birders report all of the places where Cerulean Warblers are encountered in the breeding season and estimates of the numbers encountered would give us a good start and point us in the direction of where to direct more structured efforts in order to develop a good inventory or atlas of Cerulean Warbler sites. This combined with remote habitat analysis could give us a good start on where to expect populations to occur.
I also think that casual observations, including things like the SBC, CBC and eBird can also be helpful for indicators of gross trends. While you will not be able to say x population has declined by x percent, you can say "it seems that there are a lot less Blue-winged Warblers than there were 30 years ago or a lot more Monk Parakeets...", and that can be ammunition to say that more structured efforts are needed.
Patrick Comins, Meriden.
From: ctbirds-bounces at lists.ctbirding.org
[mailto:ctbirds-bounces at lists.ctbirding.org]On Behalf Of Dennis Varza
Sent: Tuesday, March 20, 2007 11:51 AM
To: ctbirds at lists.ctbirding.org
Subject: [CT Birds] Thoughts on Bird Numbers
There have been several comments on the change in numbers of birds.
Looking at past lists is interesting and fun. But, only hints at what
changes have occurred. Often I hear comments about birders’
contribution to science, but except for certain people most birders are
out for play. Which is fine if you accept that is what you are doing.
Bird numbers are changing all the time and they need to be documented.
“I remember when” doe not cut it when trying to save habitat or
influence policy. Policy makers need hard data. A while back I realized
being a Biologist is very depressing. All the jobs are in protecting
and saving remnants, (sort of like a fireman). One doesn’t get paid to
study the mysteries of life one sees every day.
When I moved back to Connecticut I considered how to spend my time
Chasing rarities no longer held much interest. I thought about what
Lordship like 100 years ago, and that we really don’t know except from
the scraps of old records. I then thought about what kinds of records
to leave behind for the next person 100 years from now.
To be scientifically useful for the future, field notes should be
quantitative and reproducible.
Number of birds, even the common ones, is important to assess magnitude
of change. What does common, or regular really mean? These types of
description are subjective and may be obvious now but 100 year from
now? In writing a report on Red-headed Woodpeckers I found this often
cited comment that they were “as common as Flickers”. What does that
really mean? It begs the question: “Well, how common were Flickers
then?” Using numbers can give you averages, standard deviations, and
statistical tests. Their meaning is always the same. Instead of saying
“It seems to me that warblers are less common than 50 years ago”. One
can say “There was a 50% decrees in abundance over the past 50 years”.
Which statement do you think would have more weight?
Granted, counting birds takes time and the accuracy can be
questionable, but something is better than nothing. I find that
counting shorebirds in flocks over ten is usually an estimate, the way
those little buggers run about. It really doesn’t matter much if you
count 15 birds and there are really 18. As long the number is
reasonably close, it is OK. Putting down 50 birds however will cause
problems. The larger the numbers the more slop is allowed. Counting the
huge rafts of Scaup is an educated guess. With practice and experience
one can come up with reasonable numbers. When in doubt use this trick:
Bracket the number; Is there more than 1 and less than 100? Is it more
than 20 and Less than 50? Eventually you will come up with a reasonable
estimate. What really bugs me is when people put down something like
40+ Coot. What does the plus mean? They had 40 coot but there was more,
how many more, 10 more, 50 more, 100 more? Why not just give it your
best estimate and be done with it. Yesterday I was out birding and saw
The hard part is keeping running totals of the common stuff. How many
Cardinals do you see in a day birding. Unless you write down numbers as
you go you will never know. Blue Jay is a common bird, yet when you
actually stop and count the birds you see, some time only 1 or 2 are
seen for the day.
The really hard part is counting the really abundant common birds. Even
I have my limits. For the most part I do not count Common Crows. Mainly
because when I am birding I move slower than the birds and there is a
good chance I could be counting birds more than once (I will make note
of large congregations). I do not count Rock Pigeons, Monk Parakeets,
Starlings, House Sparrows, and Black=backed, Herring and Ring-billed
Gulls. Imagine trying to get a good count at Seaside Park Bridgeport at
low tide, that would kill your day. It should be done, it is just that
I haven’t figured out the best way to do it yet. Also, during the
summer I don’t count Robins, Red-winged Blackbirds and Grackles. When I
am on the shore and concentrating on counting ducks or shorebirds I
pretty much ignore the land birds because the numbers would not be
representative of what is really there.
The second part of useful record keeping is reproducibility. The number
of birds one sees is affected by many conditions. The ideal situation
is to keep all the conditions the same so that any difference in number
is due to the birds themselves and not the conditions. One major
condition is where you go. Can someone look at your notes and retrace
your steps? Birding Lordship if done thoroughly would take at least a
day, 2 during migration, Some sites I cover all the time some
occasionally. My list would vary depending upon what sites I do and
don’t cover. So, I enumerate the sites I do cover in the sequence I
cover them. so someone can retrace my steps in the future and see how
things have changed. For inland birds I created several routes and
made detailed notes about how they are covered. For 5 years I covered
the routes to create a database. In the future someone can follow my
footsteps and QUANTITATIVELY see how things have changed. By the way, I
also photographed the routes so one can see the changes in habitats.
Other things to Include is weather data, tide information, and sea
conditions, (White Caps, Calm, Rippled, Glass etc.).
Quantitate birding is very demanding with delayed gratification. I
would suggest for starters picking out your favorite (most often
birded) site and just do that.
This list is provided by the Connecticut Ornithological Association (COA) for the discussion of birds and birding in Connecticut.
For subscription information visit http://lists.ctbirding.org/mailman/listinfo/ctbirds_lists.ctbirding.org
More information about the CTBirds